One of the more common misconceptions with homes using renewable energy is that they are totally independent, off-grid setups. In the vast majority of cases, this is not true: the home remains on the grid but offsets any external energy use with renewable sources so that the net cost or net use is zero (or better).

It's important to note that anyone trying to implement renewable energy systems to achieve a net-zero or net-positive effect will almost certainly need to consult with a professional design consultant. Even if you do most of the planning yourself, it's worth getting an experienced set of eyes to review your project, to ensure you haven't made mistakes and to spot opportunities for additional efficiency gains.

There are two main system types you can implement for energy efficiency: solar thermal and renewable electricity.

Solar thermal or solar water heating uses the sun's energy to provide hot water to the home. That's it. It doesn't generate electricity and, as such, will never completely remove your dependency on grid-provided, non-renewable sources.

To achieve a net-zero or net-positive system, you'll need to tie in some renewable electricity from photovoltaic panels, a wind turbine or some other generator. You'll still likely be grid-tied, for times when your system can't handle your needs, but your annual power use from non-renewable sources should be zeroed out (or better) by what you produce yourself.